Editor's Note: See also Schedule II, Stop Signs, included at the end of Title III.
Those streets and parts of streets described by ordinances of the City are declared to be through streets for the purposes of Sections 335.010 to 335.090.
Whenever any ordinance of the City designates and describes a through street, it shall be the duty of the City Traffic Engineer to place and maintain a stop sign, or on the basis of an engineering and traffic investigation at any intersection a yield sign, on each and every street intersecting such through street unless traffic at any such intersection is controlled at all times by traffic control signals; provided however, that at the intersection of two (2) such through streets or at the intersection of a through street and a heavy traffic street not so designated, stop signs shall be erected at the approaches of either of said streets as may be determined by the City Traffic Engineer upon the basis of an engineering and traffic study.
The City Traffic Engineer is hereby authorized to determine and designate intersections where particular hazard exists upon other than through streets and to determine whether vehicles shall stop at one (1) or more entrances to any such intersection in which event he/she shall cause to be erected a stop sign at every such place where a stop is required, or whether vehicles shall yield the right-of-way to vehicles on a different street at such intersection as prescribed in Subsection (A) of Section 335.040 in which event he/she shall cause to be erected a yield sign at every place where obedience thereto is required.
A. 
The driver of a vehicle approaching a yield sign if required for safety to stop shall stop before entering the crosswalk on the near side of the intersection or, in the event there is no crosswalk, at a clearly marked stop line, but if none, then at the point nearest the intersecting roadway where the driver has a view of approaching traffic on the intersecting roadway.
B. 
Except when directed to proceed by a Police Officer or traffic control signal, every driver of a vehicle approaching a stop intersection indicated by a stop sign shall stop before entering the crosswalk on the near side of the intersection or, in the event there is no crosswalk, shall stop at a clearly marked stop line, but if none, then at the point nearest the intersecting roadway where the driver has a view of approaching traffic on the intersecting roadway before entering the intersection.
Except when directed to proceed by a Police Officer or traffic control signal, every driver of a vehicle approaching a stop intersection indicated by a stop sign shall stop as required by Subsection (B) of Section 335.040 and after having stopped shall yield the right-of-way to any vehicle which has entered the intersection from another highway or which is approaching so closely on said highway as to constitute an immediate hazard during the time when such driver is moving across or within the intersection.
The driver of a vehicle approaching a yield sign shall in obedience to such sign slow down to a speed reasonable for the existing conditions and shall yield the right-of-way to any vehicle in the intersection or approaching on another highway so closely as to constitute an immediate hazard during the time such driver is moving across or within the intersection; provided however, that if such a driver is involved in a collision with a vehicle in the intersection, after driving past a yield sign without stopping, such collision shall be deemed prima facie evidence of his/her failure to yield right-of-way.
The driver of a vehicle within a business or residence district emerging from an alley, driveway or building shall stop such vehicle immediately prior to driving onto a sidewalk or onto the sidewalk area extending across any alleyway or driveway and shall yield the right-of-way to any pedestrian as may be necessary to avoid collision and upon entering the roadway shall yield the right-of-way to all vehicles approaching on said roadway.
No driver shall enter an intersection or a marked crosswalk unless there is sufficient space on the other side of the intersection or crosswalk to accommodate the vehicle he/she is operating without obstructing the passage of other vehicles or pedestrians, notwithstanding any traffic control signal indication to proceed.
A. 
Whenever any person driving a vehicle approaches a railroad grade crossing under any of the circumstances stated in this Section, the driver of such vehicle shall stop within fifty (50) feet but not less than fifteen (15) feet from the nearest rail of such railroad and shall not proceed until he/she can do so safely. The foregoing requirements shall apply when:
1. 
A clearly visible electric or mechanical signal device gives warning of the immediate approach of a railroad train;
2. 
A crossing gate is lowered or when a human flagman gives or continues to give a signal of the approach or passage of a railroad train;
3. 
An approaching railroad train is plainly visible and is in hazardous proximity to such crossing.
B. 
No person shall drive any vehicle through, around or under any crossing gate or barrier at a railroad crossing while such gate or barrier is closed or is being opened or closed.
C. 
No person shall drive a vehicle through a railroad crossing when there is not sufficient space to drive completely through the crossing.
D. 
No person shall drive a vehicle through a railroad crossing unless such vehicle has sufficient undercarriage clearance necessary to prevent the undercarriage of the vehicle from contacting the railroad crossing.
E. 
Every commercial motor vehicle as defined in Section 302.700, RSMo., shall, upon approaching a railroad grade crossing, be driven at a rate of speed which will permit said commercial motor vehicle to be stopped before reaching the nearest rail of such crossing and shall not be driven upon or over such crossing until due caution has been taken to ascertain that the course is clear. This Section does not apply to vehicles which are required to stop at railroad crossings pursuant to Section 304.030, RSMo.